Orthogonal frequency-division multiplexing (OFDM) and orthogonal frequency division multiple access (OFDMA) wireless communication systems under IEEE 802.16 use a network of base stations to communicate with wireless devices (i.e., mobile stations) registered for services in the systems based on the orthogonality of frequencies of multiple subcarriers and can be implemented to achieve a number of technical advantages for wideband wireless communications, such as resistance to multipath fading and interference. Each base station (BS) emits and receives radio frequency (RF) signals that convey data to and from the mobile stations.
Generally, batteries provide power for most mobile stations, and therefore, power consumption is a concern for MS design engineers. For many radio access technologies (RATs), there is typically a low power standby mode to save battery power. On multi-mode wireless devices, the device may be registered to multiple network services at the same time. For example, a smart phone may be registered to both a 3G network (for voice calls and text messaging) and a WiMAX network (for high-speed Internet access) at the same time. Both 3G and WiMAX networks typically demand that the multi-mode device report to the serving BS to ensure continued communication. Even during standby modes, periodic registration may be required, and staying registered to both network systems consumes power.